We examined the dose from 99mTc contained in syringes and shielded vials to assess in detail the dose burdens in a central pharmacy.
Methods: Absorbed-dose rates at the end of the plunger of a shielded syringe, when 99mTc is contained either in the syringe or in a shielded vial from which the activity would be drawn, were measured with CaF2 dosimeters. The dose rates also were calculated with a Monte Carlo model.
Results: When activity was contained in either 3-ml or 10-ml disposable syringes shielded by lead glass, the absorbed-dose rates were 1.35-1.62 mGy hr-1 GBq-1 (5-6 mrad hr-1 mCi-1). When the activity was contained in either a shielded elution or product kit vial, the absorbed-dose rates at the end of the syringe plunger were about 0.40 mGy hr-1 GBq-1 (1.4-1.5 mrad hr-1 mCi-1). These results were reproduced with reasonable accuracy by Monte Carlo simulations.
Conclusion: The dose burden per unit of activity handled from 99mTc in procedures using syringes is likely to be two to five times larger than the dose burden from calibrating generator eluate. The Monte Carlo simulations suggest that lead K x-rays may be responsible for a significant fraction of the total dose to the fingers and hand of the pharmacist when lead-glass syringe shields are used.